/**
 * 最简单的基于FFmpeg的视频播放器SU(SDL升级版)
 * Simplest FFmpeg Player (SDL Update)
 *
 * 雷霄骅 Lei Xiaohua
 * leixiaohua1020@126.com
 * 中国传媒大学/数字电视技术
 * Communication University of Chisna / Digital TV Technology
 * http://blog.csdn.net/leixiaohua1020
 *
 * 本程序实现了视频文件的解码和显示（支持HEVC，H.264，MPEG2等）。
 * 是最简单的FFmpeg视频解码方面的教程。
 * 通过学习本例子可以了解FFmpeg的解码流程。
 * 本版本中使用SDL消息机制刷新视频画面。
 * This software is a simplest video player based on FFmpeg.
 * Suitable for beginner of FFmpeg.
 *
 * Version:1.2
 *
 * 备注:
 * 标准版在播放视频的时候，画面显示使用延时40ms的方式。这么做有两个后果：
 * （1）SDL弹出的窗口无法移动，一直显示是忙碌状态
 * （2）画面显示并不是严格的40ms一帧，因为还没有考虑解码的时间。
 * SU（SDL Update）版在视频解码的过程中，不再使用延时40ms的方式，而是创建了
 * 一个线程，每隔40ms发送一个自定义的消息，告知主函数进行解码显示。这样做之后：
 * （1）SDL弹出的窗口可以移动了
 * （2）画面显示是严格的40ms一帧
 * Remark:
 * Standard Version use's SDL_Delay() to control video's frame rate, it has 2
 * disadvantages:
 * (1)SDL's Screen can't be moved and always "Busy".
 * (2)Frame rate can't be accurate because it doesn't consider the time consumed
 * by avcodec_decode_video2()
 * SU（SDL Update）Version solved 2 problems above. It create a thread to send SDL
 * Event every 40ms to tell the main loop to decode and show video frames.
 
 macOS command line:
 gcc ./simplest_ffmpeg_player.cpp -g -o simplest_ffmpeg_player.out -framework Cocoa -I /usr/local/include -L /usr/local/lib -lSDLmain -lSDL -lavformat -lavcodec -lavutil -lswscale
 
 -framework Cocoa
 [NULL @ 0x103800600] missing picture in access unit
 
 */

#include "simplest_ffmpeg_player.h"

#define __STDC_CONSTANT_MACROS

//#ifdef _WIN32
////Windows
//extern "C"
//{
//#include "libavcodec/avcodec.h"
//#include "libavformat/avformat.h"
//#include "libswscale/swscale.h"
//#include "SDL2/SDL.h"
//};
//#else
////Linux...
//#ifdef __cplusplus
//extern "C"
//{
//#endif
//#include <libavcodec/avcodec.h>
//#include <libavformat/avformat.h>
//#include <libswscale/swscale.h>
//#include <SDL/SDL.h>
//#ifdef __cplusplus
//};
//#endif
//#endif

#include <libavformat/avio.h>
#include <libavformat/version.h>
#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>
#include <libavcodec/avdct.h>
#include <libswscale/swscale.h>
#include <SDL/SDL.h>

//Refresh
#define SFM_REFRESH_EVENT  (SDL_USEREVENT + 1)

int thread_exit=0;
//Thread
int sfp_refresh_thread(void *opaque)
{
    SDL_Event event;
    while (thread_exit==0) {
        event.type = SFM_REFRESH_EVENT;
        SDL_PushEvent(&event);
        //Wait 40 ms
        SDL_Delay(40);
    }
    return 0;
}

int player(const char* path)
{
    AVFormatContext    *pFormatCtx;
    int                i, videoindex;
    AVCodecContext    *pCodecCtx;
    AVCodec            *pCodec;
    AVFrame    *pFrame,*pFrameYUV;
    AVPacket *packet;
    struct SwsContext *img_convert_ctx;
    //SDL
    int ret, got_picture;
    int screen_w=0,screen_h=0;
    SDL_Surface *screen;
    SDL_Overlay *bmp;
    SDL_Rect rect;
    SDL_Thread *video_tid;
    SDL_Event event;
    
    const char* filepath = path;
    av_register_all();
    avformat_network_init();
    pFormatCtx = avformat_alloc_context();
    
    if(avformat_open_input(&pFormatCtx,filepath,NULL,NULL)!=0){
        printf("Couldn't open input stream.\n");
        return -1;
    }
    if(avformat_find_stream_info(pFormatCtx,NULL)<0){
        printf("Couldn't find stream information.\n");
        return -1;
    }
    videoindex=-1;
    for(i=0; i<pFormatCtx->nb_streams; i++)
        if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO){
            videoindex=i;
            break;
        }
    if(videoindex==-1){
        printf("Didn't find a video stream.\n");
        return -1;
    }
    pCodecCtx=pFormatCtx->streams[videoindex]->codec;
    pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
    if(pCodec==NULL)
    {
        printf("Codec not found.\n");
        return -1;
    }
    if(avcodec_open2(pCodecCtx, pCodec,NULL)<0)
    {
        printf("Could not open codec.\n");
        return -1;
    }
    
    pFrame=av_frame_alloc();
    pFrameYUV=av_frame_alloc();
    //uint8_t *out_buffer=(uint8_t *)av_malloc(avpicture_get_size(PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height));
    //avpicture_fill((AVPicture *)pFrameYUV, out_buffer, PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height);
    //------------SDL----------------
    if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
        printf( "Could not initialize SDL - %s\n", SDL_GetError());
        return -1;
    }
    
    
    screen_w = pCodecCtx->width;
    screen_h = pCodecCtx->height;
    screen = SDL_SetVideoMode(screen_w, screen_h, 0,0);
    
    if(!screen) {
        printf("SDL: could not set video mode - exiting:%s\n",SDL_GetError());
        return -1;
    }
    
    bmp = SDL_CreateYUVOverlay(pCodecCtx->width, pCodecCtx->height,SDL_YV12_OVERLAY, screen);
    
    rect.x = 0;
    rect.y = 0;
    rect.w = screen_w;
    rect.h = screen_h;
    
    packet=(AVPacket *)av_malloc(sizeof(AVPacket));
    
    printf("---------------File Information------------------\n");
    av_dump_format(pFormatCtx,0,filepath,0);
    printf("-------------------------------------------------\n");
    
    
    img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
    //--------------
    video_tid = SDL_CreateThread(sfp_refresh_thread,NULL);
    //
    SDL_WM_SetCaption("Simple FFmpeg Player (SDL Update)",NULL);
    
    //Event Loop
    
    for (;;) {
        //Wait
        SDL_WaitEvent(&event);
        if(event.type==SFM_REFRESH_EVENT){
            //------------------------------
            if(av_read_frame(pFormatCtx, packet)>=0){
                if(packet->stream_index==videoindex){
                    ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);
                    if(ret < 0){
                        printf("Decode Error.\n");
                        return -1;
                    }
                    if(got_picture){
                        
                        SDL_LockYUVOverlay(bmp);
                        pFrameYUV->data[0]=bmp->pixels[0];
                        pFrameYUV->data[1]=bmp->pixels[2];
                        pFrameYUV->data[2]=bmp->pixels[1];
                        pFrameYUV->linesize[0]=bmp->pitches[0];
                        pFrameYUV->linesize[1]=bmp->pitches[2];
                        pFrameYUV->linesize[2]=bmp->pitches[1];
                        sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize);
                        
                        SDL_UnlockYUVOverlay(bmp);
                        SDL_DisplayYUVOverlay(bmp, &rect);
                    }
                }
                av_free_packet(packet);
            }else{
                //Exit Thread
                thread_exit=1;
                break;
            }
        }
        
    }
    
    SDL_Quit();
    
    sws_freeContext(img_convert_ctx);
    
    //--------------
    //av_free(out_buffer);
    av_free(pFrameYUV);
    avcodec_close(pCodecCtx);
    avformat_close_input(&pFormatCtx);
    
    return 0;
}
